using System;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.X509;

namespace Org.BouncyCastle.Asn1.Ocsp
{
	public class CertID
		: Asn1Encodable
	{
		private readonly AlgorithmIdentifier    hashAlgorithm;
		private readonly Asn1OctetString        issuerNameHash;
		private readonly Asn1OctetString        issuerKeyHash;
		private readonly DerInteger             serialNumber;

		public static CertID GetInstance(
			Asn1TaggedObject	obj,
			bool				explicitly)
		{
			return GetInstance(Asn1Sequence.GetInstance(obj, explicitly));
		}

		public static CertID GetInstance(
			object obj)
		{
			if (obj == null || obj is CertID)
			{
				return (CertID)obj;
			}

			if (obj is Asn1Sequence)
			{
				return new CertID((Asn1Sequence)obj);
			}

			throw new ArgumentException("unknown object in factory: " + obj.GetType().Name, "obj");
		}

		public CertID(
			AlgorithmIdentifier hashAlgorithm,
			Asn1OctetString     issuerNameHash,
			Asn1OctetString     issuerKeyHash,
			DerInteger          serialNumber)
		{
			this.hashAlgorithm = hashAlgorithm;
			this.issuerNameHash = issuerNameHash;
			this.issuerKeyHash = issuerKeyHash;
			this.serialNumber = serialNumber;
		}

		private CertID(
			Asn1Sequence seq)
		{
			if (seq.Count != 4)
				throw new ArgumentException("Wrong number of elements in sequence", "seq");

			this.hashAlgorithm = AlgorithmIdentifier.GetInstance(seq[0]);
			this.issuerNameHash = Asn1OctetString.GetInstance(seq[1]);
			this.issuerKeyHash = Asn1OctetString.GetInstance(seq[2]);
			this.serialNumber = DerInteger.GetInstance(seq[3]);
		}

		public AlgorithmIdentifier HashAlgorithm
		{
			get { return hashAlgorithm; }
		}

		public Asn1OctetString IssuerNameHash
		{
			get { return issuerNameHash; }
		}

		public Asn1OctetString IssuerKeyHash
		{
			get { return issuerKeyHash; }
		}

		public DerInteger SerialNumber
		{
			get { return serialNumber; }
		}

		/**
		 * Produce an object suitable for an Asn1OutputStream.
		 * <pre>
		 * CertID          ::=     Sequence {
		 *     hashAlgorithm       AlgorithmIdentifier,
		 *     issuerNameHash      OCTET STRING, -- Hash of Issuer's DN
		 *     issuerKeyHash       OCTET STRING, -- Hash of Issuers public key
		 *     serialNumber        CertificateSerialNumber }
		 * </pre>
		 */
		public override Asn1Object ToAsn1Object()
		{
			return new DerSequence(hashAlgorithm, issuerNameHash, issuerKeyHash, serialNumber);
		}
	}
}
